1. Field of the Invention
The present invention relates to an exercise apparatus. More particularly, the present invention relates to a treadmill.
2. Description of the Related Art
Most treadmills are electrically powered. In operation, the endless belt on the platform of the treadmills is powered by a motor at a predetermined speed for allowing a user to walk, jog or run on the belt. Generally, electric treadmill users can preset a program containing timing variation before exercise so that the treadmill will automatically make the speed of the treadmill become faster or slower at a predetermined point according to the aforementioned program during exercise. Additionally, during exercise, the user could direct the belt to speed up or slow down through a control interface of the treadmill for allowing the user to adjust the exercising speed or change exercise modes (e.g. from walking to jogging). Even so, for the operation of the electric treadmill, it requires the user to walk or run at a speed matching that of the belt, rather than the speed of the belt matching the speed of the user. In short, users cannot immediately speed up or slow down the speed of walking, jogging or running on the electric treadmill like outdoor exercise whenever they want to.
In general, the electric treadmills are usually used for a long period of walking or running (e.g. 20, 30 minutes or more). Moreover, in current commercial treadmills, the upper limit of the adjusting range of the belt running speed is actually up to 24 to 27 km/h, that is equal to one hundred meters just in 13˜14 seconds and suitable for a short period of fast-run or sprint. Since everyone has different physical abilities, not all fast-runs or sprints are carried out under maximum-speed operation of the belt. No matter how fast the belt is, when the user performs sprint exercises on the treadmill, the belt is driven by the motor at high speed. Therefore, if the user's running speed cannot keep up with the belt speed, an accident may occur. Furthermore, if the user wants to take a break or end the exercise during the sprint exercise, the user usually has two hands grip two side handrails first, and then has two feet span the belt on two side rails. If the user wants to continue running after the break, the user would step on the belt again and keep up with the belt speed, and then the user could take the two hands off the two side rails for free swinging. It is obvious that the aforementioned motions of the break and the continuance of running have a certain degree of difficulty and danger. For the safety reason, maybe that is why many people never adjust the belt speed up to the high-speed region, even if they are able to sprint with equal speed for a short time on the ground.
Relative to the electric treadmills, nowadays there are some treadmills without electric power in the market. Rather than being powered by an electric motor, the belt is powered by the user when the user walks or runs on the treadmill to push the belt with two feet (further supplemented by inertial force of a flywheel). Generally speaking, since the belt of the non-electric treadmill is rotated with the motion of the user's two feet, the user could speed up or slow down the speed of walking, jogging or running anytime. However, the general non-electric treadmill is not suitable for sprinting. The reason is that: if a user continues to increase the running speed, the forward speed corresponding to the running motion of the user (equal to the step length multiplied by step frequency) may run faster than the sliding speed to the rear of the belt plane such that the user would be close to the front end of the treadmill. In order to keep running in an appropriate region of the belt, users will naturally restrain their running speed and thus the maximum capacity cannot be exerted, so that the desired training effect cannot be achieved.
There is one method in existence trying to solve the above problems, that is, to provide a wearing member attached to the waist or the upper body of the user, e.g. an endless strap that is able to put around the waist or the abdomen of the user, or a vest being able to be worn on the user's body. Moreover, an appropriate length of rope is connected between the wearing member and a holder fixed behind the platform. Thereby, when the user who wears the wearing member exercises on the non-electric treadmill, if the body moves forward to a predetermined position, the body will be pulled by the rope in the rear side (straightened) to restrict the further forward motion of the user. Therefore, the user could practice for quick running or sprint with normal running motion, and to freely slow down or accelerate again in the process of running. There is a disadvantage in the aforementioned method. It requires the user to wear the wearing member before the user exercises on the platform of the treadmill. For example, the user needs to put the endless strap around the waist, and to take off the wearing member from the body after the end of the exercise. It is bothersome for the user. Furthermore, since it needs to install a stationary frame for securing the rear end of the rope behind the platform, the whole device will occupy more space.
On the other hand, the treadmills are generally available only for aerobic exercises of walking, jogging or running, such functions are restricted. One type of exercise apparatus with both functions of treadmill and weight training is shown in U.S. Publication No. 2014/0274578 A1. The exercise apparatus includes a platform of an analogous non-electric treadmill. The platform has a flywheel axially mounted on one end of the front roller and a friction resistance device disposed beside the flywheel. The user can manually adjust the tightness of the resistance device through a knob driving an arcuate brake pad to press against the peripheral surface of the flywheel so as to adjust the rotational resistance of the flywheel and the front roller, namely adjusting the running resistance of the belt. In addition to walking, jogging or running, the user can adjust the resistance to a higher level for making the belt difficult to slide. Then, the user could hold the front handle with two hands, adopting a position with low center of gravity, and pushing the belt backward with two legs so as to simulate a training of pushing a weight forward on the ground (e.g. push sled). As general non-electric treadmills, while walking, jogging or running on the exercise apparatus, the belt needs to have an appropriate resistance depending on the usage condition. However, the friction resistance device is not easy to adjust the resistance to meet the requirement especially for low resistance. If change to an eddy current type resistance device, it is relatively easy to make fine adjustment, but it may not be able to provide high resistance for the weight training.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional method. Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.